Change of heart: Liberal MP Craig Laundy, who says his first year in Parliament has been an education in reality versus idealism. Photo: Janie Barrett

Liberal MP Craig Laundy has had a change of heart on the same-sex marriage debate.

And it is not good news for advocates of marriage equality.

Mr Laundy had been one of the only Coalition MPs in the class of 2013 who had come out publicly in support of a free vote on same-sex marriage, even though he did not support same-sex marriage himself for religious reasons. Last December, he told Fairfax Media, he had "zero interest" in forcing his views on other MPs.

But after a year in Parliament, the member for Reid has reviewed the situation. Mr Laundy said his experience as a politician had taught him that if the Liberal Party allowed a free vote on the matter, MPs would become the victims of vigorous lobbying to make them "vote against what they believe".

Mr Laundy said he believed both sides of the marriage equality debate would get involved.

"[The issue] is so emotive and so important to particular people that if we were to go down that path [of a free vote], we are the ones that become vilified," he said.

Advertisement

"That's not what our forefathers had in mind when they came up with a conscience vote."

Mr Laundy said his first year in Parliament had been an education in political reality versus political idealism. "Twelve months in, I now get how political lobby groups work," he said, noting that people in marginal seats would be particularly vulnerable.

Mr Laundy's change of heart is a blow to same-sex marriage campaigners within the Liberal Party. While Prime Minister Tony Abbott's firm position is that marriage should be between a man and a woman, he has said the question of whether there is a free vote on the issue within the Liberal Party would be a matter for the post-election party room.

The party room needs a bill to spark a debate. This will probably be provided by Liberal Democratic Party senator David Leyonhjelm, who is preparing to put his same-sex marriage bill on the notice paper during the sitting fortnight, which begins on Monday.

While there are only a handful of Liberal MPs who publicly support same-sex marriage, such as Communications Minister Malcolm Turnbull, Parliamentary Secretary to the Minister for the Environment Simon Birmingham and Victorian MP Kelly O'Dwyer, Senator Leyonhjelm believes there is support within the party room for a free vote.

Australian Marriage Equality has made no secret about the fact it has been targeting individual MPs with local campaigns in their electorates. Earlier this year, the Liberal Party's own in-house pollster found that 78 per cent of swing voters supported same-sex marriage.